Drafting-compasses.



1|. BACA. URAFTNG COMPASSES.

APPLICATION FILED N0v.11.1918. 1,326,818, Patented 1366.30, 1919.

2 SHETS-SHEET 1.

2 SHEETS--SHEET 2.

Patented Dm 30, 19M.

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J. BACA.

DRAFTING COMPASSES.

APPLICAUON FILED Nov. l1. 1918.

ON NN JABOSLAV BACA, OF CLEVELAND, OHIO.

DRAFTING-COMPASSES.

Specification of Letters Patent.

Patented Dec. 30, 1919.

Application filed November 11, 1918. Serial No. 262,065.

To ad whom t may concern:

Be it known that I, JARosLAv BAC/A, a citizen of the Republic of CZecho-Slovakia, residing` in the city of Cleveland, in the county of Cuyahoga and State of Ohio,have invented new and useful Tmprovements in Drafting-Compasses, of which the following is a specification.

This invention relates particularly to an improvement in a machinists drafting com pass adaptable for charting or indicating arcs or circles upon metal surfaces. The invention here contemplated embodies a slidably adjustable marking point and integral indicators arranged to operate along a pair of scales having suitable graduations indieating the radius of the circle or are to be inscribed. The arrangement and construction disclosed also embody as the object `of this invention, a. tool which shall contribute largely to precision in the character of the work performed thereby.

With these and other objects in view, my invention consists in the novel construction, combination, and relative position of the parts and members hereinafter described and shown in the accompanying drawings and particularly pointed out in the appended claims.

Referring to the drawing in which like reference characters indicate like or corresponding parts:

Figure 1, is a side elevation of a tool embodying my invention. Fig. 2, is a plan view thereof showing the top reading scale. Fig. 3, is a cross section taken on line 3 3 of Fig. 1. Fig. 4, is a side elevation of a modification providing a side reading scale. Fig. 5, is a section taken on line 5-5 of Fig. 4. Fig. 6, is a perspective View of the removable marking point.

Referring to the drawings, I provide an upper narrow bar member 10 which is held in fixed relative parallel position to the lower wide fiat scale bar 12 by the interconnecting pin 11 which has rigid connection with both of said bars by having the lower end thereof integral with the lower Scale bar 12 and its head rigidly fixed in the upper bar 10. The upper bar 10 carries, at its free end, a loosely mounted knob 13 for holding the instrument with the needle 14 on the center of the circle or arc to be described.

The top face of the lower fiat scale bar 12 is provided with inscribed, or otherwise indica-ted, scales l5 having any suitable graduations as 15A, 15B, and 15C arranged on both sides of the longitudinally extending slot 16 for the stud 17 of the slidable indicator 18 arranged to register with said graduaticns. The stud 17 is rigidly connected with the top of the block 19 which is threaded for the long screw 20 loosely mounted in the depending lugs 21 and 22 integral with the bottom face of scale bar 12. The screw 2O is confined to rotary movement only, by the knurled head 20A and end nut 20B. The lug 22 carries the center needle 14.

The marking needle 23 is fixed within the head 24 which carries a wedge-shaped block 24A removably mounted in the bottom of the block 19.

An operating arm 25, having a slidable sleeve extension 26 mounted thereon, is loosely mounted upon the pin 11 intermediate a pair of cylindrical separators 27.

It is obvious, that upon the rotation of head 20A, the marking needle 23 can be shifted with the indicators 18 to the desired radius indicated on the scales 15, or the dis tance between the marking needle 23 and the center needle 14. The instrument is held in one hand by knob 13, with the needle 14 resting on the center point, and the operating arm 25 is then moved so as to revolve, or reciprocate, the needle 23 respectively, in a circumference or arc of a circle whose center is at the point of needle 14.

In the mcdied structure, shown by Figs. i

4 and 5, the structure is similar to that above described except that, in this case, the lower scale bar 28 is arranged perpendicularly with graduated scales 29 on both sides thereof. The indicator 30 is parted to slide along the sides of bar 28 to register with the scale- 29.

Tt is thought that the foregoing description and illustrations clearly disclose the construction and operation of the invention, hence a more extended explanation is omitted.

i claim:

1. In an instrument of the kind described, the combination of an upper bar, a lower bar, a connecting member rigid with said bars, an operating arm having connection with said connecting member. a center needle on said lower bar, and a slidable marking needle on said lower bar.

2. In an instrument of the kind described, the combination of an upper bar, a lower bar, a connecting member rigid with said bers, an operating erm having connection with said connecting member, e center needle on seid lower ber, a slidable marking needle on seid lower ber, seid lower bar being provided with e seele, and an indicator slidable with said marking needle. and adapted to register with seid graduated scale.

3. In an instrument of the class described, the combination of en upper bar, a handle for seidupper bar, e lower bar, a connecting member rigid with seid bers, en operating arm pivoted to seid connecting` member, said lower bar being provided with e. slot and e scale, e peir of depending lugs from said lower bar, e Screw loosely mounted in seid lugs, e block on Said screw arranged for movement along seme, a, marking needle carried by seid block, an indicator rigid with said block and extending through seid slot for registration with said scale, and a center needle carried by one of seid lugs.

In witness whereof, I have hereunto subscribed my neme this 28th day of October, 1918.

JAROSLAV BACA. Y 

